Default settings not working with WP-CLI

[gagan0123]

Bug Description

When the plugin is activated using wp-cli the default options are not saved.

Steps to reproduce

1. Install the plugin either via GUI wp-admin/plugins.php or via CLI wp plugin install performance-lab
2. Activate the plugin using wp plugin activate performance-lab
3. Check Performance Lab plugin settings

Screenshots

Additional Context

• PHP Version: 7.4
• Plugin Version: 1.0.0-beta.1

[felixarntz]

This can be fixed together with #218, as it's the same cause for both of these problems. I'll open a PR.